Patterns of inflammmation

1. ischemia

a. infarction of epidermis (coagulated ghost cells, inflammatory crust)

b. infarction of dermis (wedge shaped; thrombosed vessels)

S8C28VA-X: Patterns related to degrees of vascular insufficiency are listed.

S8C28P14-1(xtr): In this example of angiodermatitis, vascular changes are rather subtle. A characteristic lobule of rather small vessels is outlined by green arrows. The papillary dermis is fibrotic. The reticular dermis shows activation of mesenchymal cells. The epidermis shows focal, compact hyperkeratosis, a prominent granular layer, and both a superficial and a basal unit.

S8C28P14-2: An iron stain shows focal deposits that are positive (blue). Some of the deposits, to the right of the center of the field, are in the cytoplasm of dendritic histiocytes. At the lower margin of the field, the deposits are among inflammatory cells in a perivascular space. The vessels of angiodermatitis leak; in turn, extravasated red blood cells break down to form hemosiderin deposits (angiodermatitis).

S8C28P14-3: This is a hypertrophic, spongiotic and psoriasiform dermatitis which is complicated by angiodermatitis. This association is common; the angiodermatitis tends to mask the nature of the inflammatory process. Given a choice, in the study of a disseminated cutaneous disease, a biopsy of a site other than the lower extremity will avoid the problem of separating the inflammatory process from the vaso-proliferative process. The papillary dermis is widened and is edematous, even outside the domain of the lobules of newly formed vessels. To the right, the epidermis, which extends irregularly into the papillary dermis, shows lichenoid features. There is liquefaction degeneration at the dermal-epidermal interface and, in areas, the extremities of the epithelial columns have pointed extremities. Hypertrophic lichen planus would have to be considered in the differential diagnosis. Most examples of hypertrophic lichen planus will be encountered on the lower extremities (legs); the hypertrophy is an expression of not only epidermal hyperplasia, but also of a contribution made by an associated angiodermatitis. The epidermis shows focal, mild keratinocytic dysplasia.